1. Field of the Invention
The present invention relates to a speech recognition method and an apparatus therefor, and more particularly to a speech recognition method for recognizing the input speech utilizing a model, and an apparatus therefor.
2. Related Background Art
Among the conventional speech recognition technologies, few employ models of plural speaker classes, and, even in case such models are employed, there is adopted a method of utilizing models divided into male and female speakers and selecting the model to be used prior to the execution of speech recognition. Thus, there has not been a method of utilizing an unspecified speaker model or utilizing a male model and a female model at the same time for speech recognition, and there has not existed a high-speed process utilizing such a method.
In the model preparation for speech recognition, it is generally known that higher performance of recognition can be obtained by forming details in the Hidden Markov Model (HMM) in the direction of phoneme environment. It is also becoming known that higher performance of recognition can be obtained by forming details in the direction of speaker classes, represented by genders. However, while the load of recognition process increases mainly in the output probability calculation of HMM in case of the detailed model formation in the direction of phoneme environment, the load increases both in the output probability calculation and in the language search in case of the detailed model formation in the direction of speaker classes. In speech recognition, it is desirable that speech recognition be performed in real time with a high recognition rate. It is therefore necessary to realize real-time speech recognition while improving the recognition rate thereof, and, for this purpose, it is necessary to realize a high-speed process utilizing speaker class models.